نتایج جستجو برای: leaf spectra
تعداد نتایج: 193027 فیلتر نتایج به سال:
این مطالعه برای بررسی تنوع زیستی و مشخصات اکولوژیکی تپه های گادون در منطقه سوابی پاکستان در طی سالهای 2009 تا 2010 انجام شده است. این منطقه تحت تأثیر فشارهای زیستی بدلیل از بین رفتن جنگلها و چرای بیش از حد می باشد. پوشش گیاهی منطقه دامنه وسیعی از اشکال زیستی از انواع چمن ها تا درخت بلند را در بر می گیرد. 260 گونه گیاهی متعلق به 211 جنس و 90 خانواده شناسایی گردیدند. هفتاد و هفت خانواده از دو لپه...
Leaf aging is a fundamental driver of changes in leaf traits, thereby regulating ecosystem processes and remotely sensed canopy dynamics. We explore leaf reflectance as a tool to monitor leaf age and develop a spectra-based partial least squares regression (PLSR) model to predict age using data from a phenological study of 1099 leaves from 12 lowland Amazonian canopy trees in southern Peru. Res...
Leaf reflectance and transmittance spectra are urgently needed in interpretation of remote sensing data and modeling energy budgets of vegetation. The measurement methods should be fast to operate and preferably portable to enable quick collection of spectral databases and in situ measurements. At the same time, the collected spectra must be comparable across measurement campaigns. We compared ...
Leaf age structures the phenology and development of plants, as well as the evolution of leaf traits over life histories. However, a general method for efficiently estimating leaf age across forests and canopy environments is lacking. Here, we explored the potential for a statistical model, previously developed for Peruvian sunlit leaves, to consistently predict leaf ages from leaf reflectance ...
Linking remote sensing methodology to stable isotope ecology provides a promising approach to study ecological processes from small to large spatial scales. Here, we show that δ(15)N can be detected in fresh leaf reflectance spectra of field samples along a spatial gradient of increasing nitrogen input from an N2-fixing invasive species. However, in field data it is unclear whether δ(15)N direc...
Proton nuclear magnetic resonance ((1)H NMR) spectra of leaves from 50 plant species were obtained at a spectrometer frequency of 470 MHz. Water present in leaf samples gives rise to characteristic spectral patterns. Most species show only one broad (1)H NMR peak; however, the leaves of some plants display complex, orientation-dependent spectra in which a common three-line pattern is discerned....
The invasive shrub, Acacia longifolia, native to southeastern Australia, has a negative impact on vegetation and ecosystem functioning in Portuguese dune ecosystems. In order to spectrally discriminate A. longifolia from other non-native and native species, we developed a classification model based on leaf reflectance spectra (350–2500 nm) and condensed leaf tannin content. High variation of le...
Nitrogen (N) is important for the growth of crops. Estimating leaf nitrogen concentration (LNC) accurately and nondestructively is important for precision agriculture, reduces environmental pollution, and helps model global carbon and N cycles. Leaf reflectance, especially in the visible and near-infrared regions, has been identified as a useful indicator of LNC. Except reflectance passively ac...
This paper presents a set of spectral reflectance data of numerous surface cover types of the Big Pine Creek watershed in California’s Eastern Sierra Nevada Mountains. Ground cover vegetative types include several samples of deciduous broad leaf and narrow leaf trees, needle leaf conifers, sages, and needle leaf and broad leaf shrubs. In addition, several litter samples as well as soil and rock...
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